Speaker: Matthew Kunz, Princeton University
Title: Microphysical constraints on macroscale turbulence in high-beta astrophysical plasmas
Abstract: The transport of energy and momentum and the heating of plasma particles by waves and turbulence are key ingredients in many problems at the frontiers of heliospheric and astrophysics research. This includes the heating and acceleration of the solar wind, the observational appearance of black-hole accretion flows on event-horizon scales, and the properties of the hot, diffuse plasmas that fill dark-matter halos. All of these plasmas are magnetized and weakly collisional, with plasma beta parameters of order unity or even much larger. In this regime, deviations from local thermodynamic equilibrium (LTE) and the kinetic instabilities they excite can dramatically change the material properties of such plasmas and thereby influence the macroscopic evolution of their host systems. This talk outlines an ongoing programme of hybrid-kinetic and fluid-kinetic calculations aimed at elucidating from first principles the multi-scale physics of magnetized, weakly collisional, high-beta astrophysical plasmas. Interrupting Alfvén waves, self-sustaining sound waves, microphysically modified magnetosonic modes, mirror-infested current sheets, and magneto-immutable turbulence feature in a discussion of how self-generated pressure anisotropies fundamentally alter waves, turbulence, and heating in dilute astrophysical plasmas.
Bio: Matthew Kunz is an Associate Professor and Associate Chair at Princeton University in the Department of Astrophysical Sciences and Director of Graduate Studies for the Program in Plasma Physics at the Princeton Plasma Physics Laboratory. Prof. Kunz uses analytical and numerical tools to investigate magnetic fields and multi-scale plasma dynamics in a variety of astrophysical and space systems, including molecular clouds, protostellar cores, the intracluster medium of galaxy clusters, black-hole accretion flows, protoplanetary disks, and the solar wind. He received degrees in Astronomy-Physics and Music from the University of Virginia in 2003 and a PhD in Physics from the University of Illinois at Urbana-Champaign in 2009. From 2009 to 2011, he was a postdoctoral research associate at the Rudolf Peierls Centre for Theoretical Physics at the University of Oxford. Afterwards, he moved to Princeton as a NASA Einstein Fellow and a Lyman Spitzer Jr. Fellow, joining the faculty there in 2015.
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